Force microscopy study of SrTiO3(001) surfaces with single atomic-layer steps

An atomically flat SrTiO3(001) surface was successfully obtained by combini ng ultrasonic agitation-arid subsequent annealing at 1000 degrees C in air The topographic images taken using an atomic force microscope revealed that the surface was composed of clear atomic-steps and atomically smooth terra ces. The steps were 0.2 nm in height corresponding to half of the unit cell height of SrTiO3, or the single atomic-layer height. The terraces were cat egorized into two types wide and narrow terraces appear alternately. Surfac e composition analyzed by coaxial impact collision ion scattering spectrosc opy indicated that the topmost surface was covered by domains of the SrO an d TiO2 layers, where the latter domain was dominant. The result suggests th at the topmost surface of the narrow terrace was terminated by SrO and the wide terrace by TiO2. This was further examined by the use of:a friction fo rce microscopy technique with which we were able to distinguish the differe nt surface terminations.